The earliest known 1970 car in what appears to be FM3 is the auto show 1970 Challenger R/T convertible & the paint code on it is 999. Did it stir up enough interest to add the color to the lineup? Could be, but we may never know for sure.
The Challenger show car likely was a promotional introduction for a color that was going to be in the books midyear.
Not sure what the 15A thing is you talk about....I saw a tag with the code, but I don't know what color it references nor do I know what car it was.
